There are many applications in the use of fasteners where the parts are being fastened in locations where access to the rear of the members is impossible or the hole in the second member is a blind hole. In such circumstances it is impossible to retain one portion of the fastener assembly in fixed position while the other portion is rotated so as to bring the fastener into a position where it locks the two members together. This type of situation frequently occurs when dealing with panel to panel arrangements.
There have been many suggested solutions to the problem and there is always room for further improvements to advance the dependability of the fastener for repeated use and for use of a large number of fasteners in many different environments.